|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
dcummins
Joined: 14 Feb 2017
Last visit: 16 Mar 2026
Posts: 1,021
Own Kudos:
Given Kudos: 368
Location: Australia
Concentration: Technology, Strategy
Schools: INSEAD Sept'21 Intake (WA$$$) Melbourne (A$$$$) AGSM (A$$$$) Kellogg '23 (WL) Said '22 (A$$$$) CBS '23 (D) Booth '23 (WA) Anderson '23 (WA) Cambridge '22 (WL) LBS '23 (D) Stern '24 (WA)
GMAT 1: 560 Q41 V26
GMAT 2: 550 Q43 V23
GMAT 3: 650 Q47 V33
GMAT 4: 650 Q44 V36
GMAT 5: 600 Q38 V35
GMAT 6: 710 Q47 V41
WE:Management Consulting (Consulting)
Products:
Schools: INSEAD Sept'21 Intake (WA$$$) Melbourne (A$$$$) AGSM (A$$$$) Kellogg '23 (WL) Said '22 (A$$$$) CBS '23 (D) Booth '23 (WA) Anderson '23 (WA) Cambridge '22 (WL) LBS '23 (D) Stern '24 (WA)
GMAT 6: 710 Q47 V41
Posts: 1,021
Kudos:
2,379
18 Aug 2019, 18:25
Kudos
Bookmarks
The only ways the child won't land a head AND a tail is if he or she lands ALL heads and ALL tails
i.e. HHHHH or TTTTT
So we can deduct the probability that these two events will occur from 1 to determine the Probability that either won't occur and thus that at least 1 head AND tail will land.
P(all heads) = (1/2)^5 * 5!/5! = 1/32
P(all tails) = (1/2)^5 * 5!/5! = 1/32
Add together= 2/32 = 1/16
deduct from 1
1-1/16
=15/16
i.e. HHHHH or TTTTT
So we can deduct the probability that these two events will occur from 1 to determine the Probability that either won't occur and thus that at least 1 head AND tail will land.
P(all heads) = (1/2)^5 * 5!/5! = 1/32
P(all tails) = (1/2)^5 * 5!/5! = 1/32
Add together= 2/32 = 1/16
deduct from 1
1-1/16
=15/16
18 Aug 2019, 18:57
Kudos
Bookmarks
nikdiablo129
No of ways to get at least 1 head and 1 tail in flip of a coin 5 times= Total no of ways to flips a coin 5 times - no of ways to flip all heads - no of ways to flips all tails= 2^5 - 1-1= 32-12= 30
Total no of ways to flip a coin 5 times = 2^5=32
Probability of flipping a coin to get at least 1 head and 1 tail = 30/32=15/16
IMO C
Alternatively
Probability of getting at least 1 head and at least 1 tail = 1 - probability of getting all heads - probability of getting all tails = 1 -1/32-1/32=1-2/3230/32=15/16
IMO C
Posted from my mobile device
vaibhav1221
Joined: 19 Nov 2017
Last visit: 24 Jul 2025
Posts: 292
Own Kudos:
Given Kudos: 50
Location: India
Schools: IIMA '25 (A) Columbia CBS'26 (D) Fuqua '26 (D) ISB '25 (WL) Darden '26 (D) Kenan-Flagler '26 (WL)
GMAT 1: 710 Q49 V38
GPA: 3.25
WE:Account Management (Advertising and PR)
Schools: IIMA '25 (A) Columbia CBS'26 (D) Fuqua '26 (D) ISB '25 (WL) Darden '26 (D) Kenan-Flagler '26 (WL)
GMAT 1: 710 Q49 V38
Posts: 292
Kudos:
410
20 Aug 2019, 00:59
Kudos
Bookmarks
Total number of outcomes = 2^5 = 32
there will be only one outcome where there result is TTTTT
and there will be only one outcome where the result is HHHHH
rest will be a combination of H and T.
Favorable outcomes 32-2 = 30
Probability = 30/32 = 15/16
there will be only one outcome where there result is TTTTT
and there will be only one outcome where the result is HHHHH
rest will be a combination of H and T.
Favorable outcomes 32-2 = 30
Probability = 30/32 = 15/16
